John Schnatter accuses board of asking him to step down as chairman ‘without apparently doing any investigation’ into his use of a racial slur

The founder of Papa John’s International Inc. vowed to fight the pizza chain over how it pressed him to step aside for his use of a racial slur, in a controversy that is casting fresh attention on the handling of race issues in corporate America.

John Schnatter last week publicly apologized for using the slur during media training over the phone with a marketing agency, which was intended to prepare him for returning to his role as brand spokesman. Days later, in a letter to the directors reviewed by The Wall Street Journal,...